Helminthosporium camelliae-sinensis M.F. Chi & Jian K. Liu, 2025

Helminthosporium camelliae-sinensis M.F. Chi & Jian K. Liu , sp. nov.

MycoBank number: MB 903757; Facesoffungi number: FoF 17678. Fig. 2 View FIGURE 2

Etymology: —The species epithet ‘ camelliae-sinensis ’ refers to the host from which the fungus was originally isolated.

Holotype:—HAKS 144246

Saprobic on dead twigs of tea ( Camellia sinensis L.). Sexual morph: Undetermined. Asexual morph: Colony on natural substrate superficial, effuse, hairy, dark brown to black, glistening. Mycelium superficial, numerous, hairy, black, scattered, solitary or fasciculate, septate, unbranched, smoothed, thick‐walled hyphae. Conidiophores 269– 842 µm long ( x = 541 µm, n = 20), 15–23 µm wide ( x = 18 µm, n = 20), macronematous, mononematous, erect, simple, smooth, thick‐walled, subcylindrical, straight to slightly curved, septate, dark brown to black, obtuse at apex. Conidiogenous cells mono- to poly‐tretic, integrated, terminal and intercalary, cylindrical, brown, smooth. Conidial secession schizolytic. Conidia 33–77 µm long ( x = 48 µm, n = 40), 8–15 µm wide ( x = 11 µm, n = 40), tapering to 3.8–8.6 µm ( x = 6.2 µm, n = 20) at the distal end, with a blackish-brown 3–5 µm ( x = 4 µm, n = 40) wide scar at the base, 5-8 distoseptate; with an angular lumina, wall up to 2.3–3.5 µm ( x = 2.8 µm, n = 20) thick, cylindrical, obclavate, phragmoconidia, acropleurogenous, straight or curved, uneven width, rounded at apex, thick-walled, light green brown to medium brown.

Culture characteristics: —Conidia germinating on PDA within 24 h and germ tubes arising from cells of the arms. Colonies growing on PDA reached a diam. of 21 mm after two weeks at 25 °C. Flower-shaped, anomalistic, white-edged, internally pale green and obvious circles, reverse almost yellowish-brown with pale yellow edges.

Material examined:— CHINA, Sichuan Province, Qionglai City, Tiantaishan Town , 30°15′58''N, 103°6′25''E, 1,000–1,250 m, on dead tea twigs ( Camellia sinensis ), 18 September 2023, M.F. Chi, X.D. Liang T24-1 (HKAS 144246, holotype; ex-type living culture, CGMCC 3.27822) GoogleMaps ; ibid., T24-2 (HUEST 24.0218, paratype; living culture, UESTCC 24.0201) GoogleMaps .

Notes:— Phylogenetic analysis of the combined dataset, including ITS, LSU, SSU, rpb 2 and tef 1-α loci, revealed that our collection forms a distinct clade closely related to Helminthosporium yunnanense (HJAUP C2071) and H. austriacum (CBS 139924, CBS 142388) ( Fig. 1 View FIGURE 1 ). In the NCBI BLASTn search, the closest match to our isolate (UESTCC 24.0201) was H. austriacum (CBS 139924). A comparison of ITS, LSU, SSU, rpb 2, and tef 1-α sequences from our collection with the type strain of H. austriacum (CBS 139924) showed 95.95% similarity (474/494 bp, 1 gap), 99.41% similarity (842/847, 2 gaps), 99.90% similarity ( 1,024 / 1,025, 1 gap), 97.85% similarity ( 1,002 / 1,024, without gaps), and 97.61% similarity (735/753, without gaps), respectively. Morphologically, the conidiophores of our collection (269–842 × 15–23 µm) are shorter and wider than those of H. austriacum (275–700(–920) × 11.5–19 µm) ( Voglmayr et al. 2017), and longer and wider than those of H. yunnanense (560–680 × 12.5–15.5 µm) ( Liu et al. 2022). Our collection has 5-8 distoseptate conidia, which are more than those of H. yunnanense (4-7 distoseptate) but fewer than H. austriacum (4-10 distoseptate). While the conidia of both H. austriacum and H. yunnanense are pale brown, the conidia of our collection exhibit a slightly greenish-brown color ( Hu et al. 2023). The shape of the conidia of our collection is obclavate and lunate, differing from the obpyriform to lageniform shape of H. austriacum and the obclavate, sigmoid shape of H. yunnanense . Additionally, our collection's conidia are wider (15–23 µm) compared to H. yunnanense (9–11 µm) and H. austriacum (10.0–19.8 µm) ( Hu et al. 2023). Thus, based on these morphological observations and phylogenetic evidence, our collection is described as a new species.